UC San Diego Researches Discover Why We Sunburn

Overexposure to the sun can cause pain, swelling, and red and itchy skin. But until recently, scientists didn’t know why we respond this way to ultraviolet radiation.

Researchers at UC San Diego have discovered what triggers a sunburn.

"Previous to this we knew that the sun killed cells and damaged cells and caused cancer, and we knew the skins response to that was inflammation, but we couldn’t link the two together,” said Richard L. Gallo, professor of medicine at UCSD and lead author of the study.

Sun exposure causes cancer by damaging DNA. Gallo and his team discovered that the sun also damages a related molecule, RNA.

"This damaged RNA is sensed by other cells as a signal of injury. Almost like when a bacteria or virus gets on the skin or in your cell you react with inflammation," Gallo said.

This inflammation is sunburn and it's our bodies’ immune response to sun exposure.

Gallo said understanding how the skin reacts to sunlight can help prevent cancer, and could lead to developing treatments for patients with abnormal reactions to the sun.

The paper was published in the advanced online publication of Nature Medicine.